1. Field of the Invention
This invention generally relates to video decoding and more specifically to reducing memory requirements during decoding.
2. Background Art
A visual information source requires a transmission or a storage medium to convey its message to the observer. The fidelity of transmission and reproduction of the message is closely related to and dependent on the available medium capacity and the manner in which it is used. Storage medium capacity is typically expressed in bits per second or a bit rate. The amount of storage required for digital media can be reduced by compressing the video signal. Digital video compression is used to represent an image with as low a bit rate as possible while preserving an appropriate level of picture quality for a given application. Compression is achieved by identifying and removing redundancies in digital media. A bit rate reduction system operates by removing redundant information from the signal at the encoder prior to transmission and re-inserting it at the decoder. An encoder and decoder pair are referred to as a ‘codec’.
At its most basic level, compression is performed when an input video stream is analyzed and information that is indiscernible to the viewer is discarded. Each event is then assigned a code where commonly occurring events are assigned fewer bits and rare events are assigned more bits. These steps are commonly referred to as signal analysis, quantization and variable length encoding. Common methods for encoding or compression include discrete cosine transform (DCT), vector quantization (VQ), fractal compression, and discrete wavelet transform (DWT). Methods for decoding or decompression are typically the inverse of the methods used for encoding. However, full-resolution decoding is memory intensive requiring significant storage resources along with extensive data transfer bandwidth. Method and systems are needed to overcome the above deficiencies.
The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers may indicate identical or functionally similar elements.